A team of researchers from the Australian National Univeristy (ANU) have made a significant achievement that could bring quantum computing and the much anticipated quantum internet closer to reality. In a study published in the journal Nature Physics, the team led by ANU Research School of Physics associate professor Matthew Sellars found a way to extend the data storage time of quantum systems using crystals treated with a rare-Earth element called erbium.
“We have shown that an erbium-doped crystal is the perfect material to form the building blocks of a quantum internet that will unlock the full potential of future quantum computers,” Sellars said in an ANU press release. “We had this idea 10 years ago, but many of our peers told us that such a simple idea couldn’t work. Seeing this result, it feels great to know that our approach was the right one.”
The so-called building blocks of quantum computers and a quantum internet are quantum bits (or qubits), which are entangled particles that can carry information simultaneously as both ones and zeroes. Compared to binary bits in conventional computers, which can only be a 0 or a 1 at a given moment, qubits allow for processing significantly more information faster. The challenge has been in prolonging the entangled state, and thereby extending the length of time data can be stored.
Sellars and his team approached the problem from an engineering perspective. By using erbium crystals, with their unique quantum properties, the ANU team were able to successfully store quantum information for 1.3 seconds. That’s a quantum memory that’s 10,000 times longer compared to other efforts. Plus, it eliminates the need for a conversion process since the erbium crystals operate in the same bandwidth as current fiber optic networks.
“At the moment researchers are using memories that don’t work at the right wavelength, and have to employ a complicated conversion process to and from the communications wavelength,” ANU researcher Rose Ahlefeldt explained. “This can be inefficient, and means they have to do three very difficult things instead of just one.”
While we’ve already demonstrated long-distance quantum entanglement, extending the length of time data can be stored in a quantum memory is important in perfecting quantum communication, which is crucial in the development of a quantum internet. This kind of quantum network promises faster information transfer, as well as “hack-proof” communication because it uses a type of encryption that keeps messages and information secure via a quantum key. In short, tampering with messages sent through a quantum internet is nearly impossible.
“The effort to build a quantum computer is often described as the space race of the 21st century,” Sellars said. Prolonging quantum memory is crucial in that race, and their technology can help do that. Plus, it can also be used to connect many types of quantum computers. Sellars added that it “will allow us to build a global network to connect quantum computers” — i.e., a quantum internet.